Method of producing an air cushion and an apparatus for the same

Abstract

Two-ply films 23, 24 are sent and heat-fused in a longitudinal direction and a transverse direction on a heat drum-roller 30, furthermore, hollow bubble portions 63 with an air-leading groove 32 and bubble-forming depressions 33, provided on a circumferential surface of the heat drum-roller, and a communicating portion 62 going through sealed portions in the direction transverse to the longitudinal direction to make communication between the bubbles, are formed on the film, in order that each bubble is expanded by feeding into the hollow bubble portion 63 with air, sent from an air-blowing nozzle 40 through the communication portion 62, and then, the communicating portion 62 communicating the expanded bubbles is sealed with a point-seal 50. Therefore, an air cushion sheet 60 having plural independent bubbles 65 which are each formed in a large long type in the transverse direction is easily and certainly produced.

Claims

1. An air cushion comprising:

two plastic films that are stacked together and that extend in an elongated direction; and

at least two longitudinally extending seals and a plurality of transverse seals that extend between the plastic films to connect the plastic films together, the longitudinally extending seals extending in a longitudinal direction of the plastic films and the transverse seals extending between the longitudinally extending seals, wherein:

the plastic films define bubbles that extend between the seals and that are expanded by air and the seals are further formed and arranged so that the bubbles have a length measured in a transverse direction of the plastic films that is at least twice the diameter of the bubbles measured in the longitudinal direction of the film; and

each transverse seal is comprised of a plurality of first seal portions that are separated by at least one opening therebetween and at least one second seal portion that closes the at least one opening between the first seal portions.

2. The air cushion according to claim 1, wherein adjacent first seal portions of the transverse seals have ends that define the opening between the first seal portions and each second seal portion is connected to the ends of the first seal portions that define the opening closed by the second seal portion.

3. The air cushion according to claim 1, wherein the ends of the first seal portions are provided with supplemental seals that extend transverse to the first seal portions and the second seal portions are connected to the supplemental seals.

4. The air cushion according to claim 1, wherein the second seal portions of the transverse seals are arranged in a continuous pattern so that the second seal portions abut each other and extend across the bubbles so that the second seals further divide each bubble into at least two smaller bubbles.

5. The air cushion according to claim 4, wherein the ends of the first seal portions are provided with supplemental seals that extend transverse to the first seal portions and the second seal portions that close the openings between the first seal portions are connected to the supplemental seals.

6. A method for forming an air cushion comprising the steps of:

selectively bonding two plastic films together to form at least two longitudinally extending seals and a plurality of transverse seals that extend between the longitudinally extending seals, wherein the transverse seals are interrupted by intermittent openings;

blowing air into the intermittent openings so as to cause the expansion of the plastic films extending between the longitudinally extending seals and the transverse seals; and

closing the intermittent openings so that the expanded plastic film forms an independent bubble that extends between the longitudinally extending seals and the transverse seals.

7. The method of forming an air cushion of claim 6, wherein when the longitudinally extending seals and the transverse seals are formed, supplemental seals are formed at the ends of the transverse seals that define the intermittent openings, the supplemental seals extending in the longitudinal direction around the intermittent openings.

8. The method for forming an air cushion according to claim 1, a further improvement comprising the step of sealing across the bubbles in a longitudinal direction to divide each bubble into a plurality of bubbles when the intermittent openings are closed.

9. The method for forming an air cushion according to claim 6, wherein the seals are spaced apart from each other so that the bubbles have a length measured in the transverse direction of the film that is at least twice their diameter measured in the longitudinal direction of the film.

10. The method for forming an air cushion according to claim 6, a further improvement comprising the step of using a heat drum-roller to bond the plastic films together, wherein the heat-drum roller has a circumferential surface along which an air-lead groove is formed, the air-lead groove being aligned with the intermittent openings when the longitudinal directional seals and the transverse seals are formed and wherein the heat-drum roller is continuously rotated.

11. The method for forming an air cushion according to claim 6 wherein:

the plastic films are bonded together so that the longitudinal direction seals and the transverse seals define hollow bubble portions of plastic film that extend transversely across the film and that are arranged sequentially longitudinally along the film and, simultaneously with the formation of the hollow bubble portions, a communicating tube is formed by the film, said communicating tube extending longitudinally along the film and being in fluid communication with the hollow bubble portions so as to define the intermediate openings between the transverse seals;

the blowing air step is performed by blowing air into the communicating tube so as to cause the expansion of the hollow bubble portions of the plastic film; and

the closing step is performed by heat-fusing sections of the communicating tube closed to close the expanded hollow bubble portions of the plastic film.

12. The method for forming an air cushion according to claim 11, further comprising the step of using a heat drum-roller having plural bubble-forming depressions extending in an axial direction of the circumferential surface and a non-welding groove continuously cycled in the circumferential direction to communicate in conjunction with the bubble-forming depressions to form the longitudinal direction seals and the transverse seals.

13. An apparatus for producing an air cushion, comprising:

film-feeding means for moving two plastic films in a forward direction;

first heat-fusion means for receiving the plastic films from said film-feeding means for heat sealing the plastic films together to form at least two spaced apart longitudinally extending seals that extend in the direction in which the films are moved and a plurality of transverse seals that extend in a direction transverse to the direction in which the films are moved wherein the transverse seals are formed to define intermittent openings between the transverse seals;

an air blowing nozzle for receiving air and directing the air into the intermittent openings to cause the expansion of sections film between the longitudinally extending seals and the transverse seals; and

second heat-fusion means for heat fusing the intermittent openings closed so that the sections of expanded film form independent bubbles that extend between the longitudinally extending seals and the transverse seals.

14. The apparatus for producing the air cushion according to claim 13, wherein the first heat-fusion means is a heat drum-roller having a circumferential air-leading groove positioned to subtend the intermittent openings.

15. An apparatus for producing an air cushion, comprising:

film-feeding means for moving two plastic films in a forward direction;

first heat-fusion means for receiving the plastic films from said film-feeding means for heat sealing the plastic films together to form a plurality of hollow bubble portions which extend transverse to the direction in which the plastic films are moved and a communicating tube that is in fluid communication with the hollow bubble portions, the communicating tube extending in the direction in which the plastic films are moved;

an air blowing nozzle for receiving air and blowing air into the communicating tube so as to cause the hollow bubble portions to fill with air and expand; and

second heat-fusion means for heat-fusing the communicating tube closed to isolate the expanded bubble portions from each other.

16. The apparatus for producing the air cushion according to claim 15, wherein the first heat-fusion means is a heat drum-roller having a plurality of bubble-forming depressions that extend in an axial direction of a circumferential surface of the roller and a circumferentially extending air-leading groove that communicates with the bubble-forming depressions.

17. The apparatus for producing the air cushion according to claim 16, wherein the bubble-forming depressions are formed to have a narrower width adjacent the air-leading groove than the portions of the bubble-forming depressions distal from the air-leading groove.